A polyester elastomer is referred to as a thermoplastic elastic material having an ester type chain structure. A polyester elastomer is an intermediate material of rubber and plastic, which has flexibility and elasticity equal to those of vulcanized rubber, and which can be formed into a product by molding a general thermoplastic material such as polyethylene, polypropylene, polyamide, polyester or the like without performing a conventional vulcanizing process for preparing vulcanized rubber.
Generally, vulcanized rubber is formed by vulcanizing a natural low-viscosity rubber material or an artificially synthesized low-viscosity rubber material. However, such a rubber material exhibits excellent flexibility and elasticity, but is problematic in that its molding process is very complicated, its stability is poor and it cannot be easily recycled because it is a thermosetting material. Therefore, it has been required to develop novel materials that can overcome the above problems. In accordance with such a requirement, various kinds of thermoplastic elastomers (TPEs) such as styrene-based elastomers (first developed), urethane-based elastomers, olefin-based elastomers, amide-based elastomers and the like have been developed.
Among these thermoplastic elastomers, a polyester elastomer is a material developed earlier than other materials, and is known to be generally excellent in terms of performance and stability compared to other thermoplastic elastic materials. However, recently, the level of long-term use characteristics, such as durability, weatherability and the like, required in various uses, has become high, and excellent mechanical properties similar to those of engineering plastics have been required.
As an application example of such a polyester elastomer, there is an elastic monofilament. Generally, elastic monofilaments are most widely used to prepare spandex containing polyurethane as a substrate. Spandex is widely used in the fields of clothing to industry. However, application examples of a poly-ether-ester elastic monofilament is not frequent because its elasticity is lower than that of a polyurethane elastic monofilament, but is expected that it will be advanced because it has excellent mechanical properties, heat resistance, chemical resistance and the like.
When an elastic monofilament is prepared using a poly-ether-ester elastomer, it exhibits excellent chemical resistance compared to an elastic monofilament prepared using a general polyurethane resin. However, an elastic monofilament prepared by only a resin itself without special prescription is disadvantageous in terms of long-term durability.
As examples of attempts to improve the durability of a poly-ether-ester elastomer, U.S. Pat. No. 3,723,427 proposes tris(hydroxybenzyl)cyanurate as a sterically-hindered phenol-based primary stabilizer. Further, U.S. Pat. No. 3,758,579 proposes a thioester-type secondary stabilizer and discloses a method of mixing a thioester-type secondary stabilizer with a phenol-based primary stabilizer. Thereafter, similar technologies for improving stability by mixing such primary and secondary stabilizers to cause a synergistic effect were disclosed in U.S. Pat. Nos. 3,996,675, 4,414,408, etc. Among them, U.S. Pat. No. 4,069,200 discloses a technology for improving the durability of a polyolefin resin by independently using a sterically-hindered phenol-based primary stabilizer such as 6-tertiary-butyl-2,3-dimethyl-4-(dimethylaminomethyl)-phenol, 6-tertiary-octyl-2,3-dimethyl-4-(dimethylaminomethyl)-phenol, 6-tertiary-butyl-4-(dimethylaminomethyl)-5,6,7,8-tetrahydro-1-naphthol, 5-tertiary-butyl-2,3-dimethyl-4-hydroxybenzylphosphonate or the like, or by mixing the sterically-hindered phenol-based primary stabilizer with a thioester-type secondary stabilizer such as dilaurylthiopropionate, distearylthiopropionate or the like. U.S. Pat. No. 4,185,003 discloses a technology for improving the stability of a co-poly-ether-ester resin by mixing a phenolic antioxidant such as N,N′-hexamethylene-bis(3,5-di-t-butyl-4-hydroxyhydrocinnamamide), N,N′-trimethylene-bis(3,5-di-t-butyl-4-hydroxyhydrocinnamamide) or the like with a sterically-hindered amine photostabilizer such as bis(1,2,2,6,6-pentamethyl-4-piperidinyl)-n-butyl-(3,5-di-t-butyl-4-hydroxybenzyl)malonate, bis(2,2,6,6-tetramethyl-4-piperidinyl), bis(3,5-di-t-butyl-4-hydroxybenzyl)malonate or the like. U.S. Pat. No. 4,405,749 discloses a technology for improving the stability of a polyester resin by using trimester compounds of 1,3,5-tris-(2-hydroxyethyl)-s-triazine-2,4,6-(1H,3H,5H)trione and 3,5-di-t-butyl-4-hydroxy hydrocinnamic acid. Further, Japanese Examined Patent Application Publication No. 88-38371 discloses a method of preparing a stabilizer containing a large amount of a 2,2,4-trimethyl-1,2-dihydroquinoline dimer, Japanese Examined Patent Application Publication No. 88-40817 discloses a method of mixing a 2,2,4-trimethyl-1,2-dihydroquinoline compound with a phenothiazine compound, and Japanese Examined Patent Application Publication No. 88-40819 discloses a method of improving stability by mixing a 2,2,4-trimethyl-1,2-dihydroquinoline compound with a mercapto compound such as 2-mercaptobenzoimidazole, 2-mercaptomethylbenzoimidazole or the like.
However, when a thermoplastic poly-ether-ester elastomer, unlike polyethylene terephthalate or polybutylene terephthalate, is thermally decomposed, its polyol portion, which is a soft segment, is first decomposed to produce formic acid, and the produced formic acid accelerates the decomposition of the thermoplastic poly-ether-ester elastomer. In this case, in order to prevent the acceleration of the decomposition thereof, it is required to capture formic acid. Generally, the capturing of formic acid can be conducted by basic materials, but, among basic materials, amine-based stabilizers are to problematic in that they deteriorate the initial color of a product although they have excellent heat resistance.
Further, when elastic monofilaments prepared using a polyester elastomer are woven and left for a long period of time, they give off a stench that stimulates a consumer's displeasure. This stench is caused by various kinds of volatile inorganic compounds generated by the thermal decomposition of a polyester elastomer during weaving and post-treatment processes. Particularly, in the case of a polyester elastomer, tetrahydrofuran (THF) is one of the main causes of this stench.
As part of the VOC removing technology for perceived quality improvement, a method of synthesizing a silica-based porous material having a uniform pore size distribution using a surfactant as a mold by a sol-gel process was reported in 1992. Thereafter, research into such a silica-based porous material has been conducted. Particularly, since such a silica-based porous material has a large specific area and comparatively high environmental stability, the possibility of the silica-based porous material being practically applied to an adsorbent is high.
When a silica-based porous material is used as an absorbent of non-polar organic materials or volatile organic compounds (VOCs), there are several problems. First, since these materials are non-polar, they cannot be easily removed by adsorption. Second, since a silica-based porous material has hydrophilicity, it first adsorbs water when it is used as an adsorbent, so it is difficult to selectively adsorb organic materials from a mixture of organic materials and water, and it is easily decomposed by water.
Generally, attempts to remove VOCs using such a silica-based porous material place the focus on the removal of various aldehydes generated from building materials and the like. For example, Korean Unexamined Patent Application Publication No. 2002-7010109 discloses a deodorant composition including at least one selected from among hydrazides, azoles and azines as an effective ingredient in order to efficiently remove aldehydes, such as acetaldehyde, formaldehyde and the like, which are bad smell components.
Further, Korean Unexamined Patent Application Publication No. 2000-0072730 discloses a method of removing free formaldehyde remaining in an amino resin such as a urea resin or the like, which is prepared by polycondensing formaldehyde and urea, by adding a predetermined amount of an aqueous ammonium acetate or ammonium bicarbonate solution at a predetermined temperature to convert free formaldehyde into formaldehyde and produce hexamine and an acid.
Further, Korean Unexamined Patent Application Publication No. 1995-006486 discloses an odorless urea adhesive, which does not emit a bad smell, using barium hydroxide [Ba(OH)2] as a catalyst and which can be used in various applications.
Further, Korean Unexamined Patent Application Publication No. 1993-00165 discloses a method of removing free formaldehyde remaining in a formaldehyde resin, including the steps of: introducing ammonium hydrogen carbonate or ammonium carbonate into a formaldehyde resin as a remover for free formaldehyde at a temperature of 40˜60° C. after the polycondensing reaction of the formaldehyde resin; stirring the formaldehyde resin for 30 minutes to 1 hour to conduct a free formaldehyde removing reaction; and adding an alkali metal hydroxide such as potassium hydroxide, sodium hydroxide or the like to the formaldehyde resin to adjust the pH of the formaldehyde resin to 7˜8.
As described above, there are methods of removing formaldehyde using an ammonium salt or using barium hydroxide as a catalyst. However, these methods are problematic in that they cannot be easily used in processes of preparing an engineering plastic or a thermoplastic elastomer. The reason for this is that it is not easy to treat and store the above-mentioned VOC reducing materials, and it is difficult to directly introduce these VOC reducing materials into the processes of preparing an engineering plastic or a thermoplastic elastomer. Thus, in the present invention, such a problem is solved using a synthetic porous silica material having excellent VOC removal performance.